1. Field of the Invention
The present invention relates to a connection terminal, more specifically to a connection terminal press-contacting with a male terminal by flexure deformation of a blade spring.
2. Description of the Related Art
A conventional connection terminal is disclosed in Japanese Unexamined Patent Publication No. S59-3877. As shown in FIGS. 1 and 2, a connection terminal 100 comprises a wire connection unit 101 and a terminal connection unit 102. The wire connection unit 101 is connected to the terminal connection unit 102.
The wire connection unit 101 has a base portion 103 and a pair of tightening flaps 104, 104. The tightening flaps 104, 104 are installed to the base portion 103 in a standing manner. A distal end of a wire (not shown) is disposed in room formed by the base portion 103 and the tightening flaps 104, 104. The wire is connected to the wire connection unit 101 by tightening the distal end of the wire with the tightening flaps 104, 104.
The terminal connection unit 102 has a base portion 105, a pair of side wall portions 106, 106, a pair of upper wall portions 107, 107 and a blade spring 108. The side wall portions 106, 106 are installed to the base portion 105 in a standing manner. A pair of supporting plates 106a, 106a are mounted to a front end and a rear end of the side wall portion 106, respectively. The upper wall portions 107, 107 extend from upper ends of the side wall portion 106, 106 toward a center portion of the terminal connection unit 102. The blade spring 108 is disposed in room formed by the side wall portions 106, 106 and the upper wall portions 107, 107 and supported by the supporting plates 106a, 106a, 106a, 106a. The blade spring 108 has a front portion 108a, a center portion 108b and a rear portion 108c and projects downward at the center portion 108b when being installed to the terminal connection unit 102.
In the above configuration, when a male terminal 110 is inserted in the terminal connection unit 102 along an insertion direction F, a distal end of the male terminal 110 butts the front portion 108a located at an insertion side of the blade spring 108. If the male terminal 110 is further inserted in the terminal connection unit 102, the blade spring 108 receiving a contact load from the male terminal 110 at the front portion 108a is flexibly deformed. The deformed blade spring 108 allows the male terminal 110 to be furthermore inserted over the front portion 108a. When the male terminal 110 is gradually inserted in the terminal connection unit 102 against reaction force generated by the flexure deformation of the blade spring 108, the male terminal 110 slides on the front portion 108a and then on the center portion 108b and the base portion 105 to reach to the rear portion 108c. The terminal connection unit 102 press-contacts with the male terminal 110, which is inserted to a given position, by means of the reacting force.
In the blade spring 108, spring strength of the front portion 108a is set to be approximately equal to that of the rear portion 108c. Therefore, in an insertional process of the male terminal 110, the blade spring 108 is flexibly deformed as a whole by pressing the male terminal 110 against the front portion 108a. If, as shown in FIG. 3A, we assume that letters A and B are respectively assigned to contact loads received by the blade spring 108 at the front portion 108a and the rear portion 108c, the male terminal 110 receives reacting force C, which is approximately equal to A+B, of the blade spring 108 from the beginning of inserting the male terminal 110 in the terminal connection unit 102 as shown in FIG. 3B.
Therefore, the male terminal 110 must be strongly pressed against the front portion 108a in order to be inserted inside the terminal connection unit 102. This leads to a poor insertional operation of the male terminal 110.